<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>Insert title here</title>
		<style type="text/css">
			#big{
				width:300px;
				
				background-color: green;
			}
			#d1{
				width:120px;
				height:80.1px;
				background-color: red;
				float:left;
			}
			#d2{
				/* 禁止元素左右两侧有浮动 */
				
				width:120px;
				height:80px;
				background-color: yellow;
				float:left;
				overflow:hidden;
				
			}
			#d3{
				width:120px;
				height:80px;
				background-color: blue;
				float:left;
			}
		</style>
	</head>
	<body>
		<div id="big">
			<div id="d1"></div>
			<div id="d2"></div>
			<div id="d3"></div>
		</div>
	</body>
</html>